Looking to find more information regarding these two camera lenses? Check out our side by side comparison of the Tamron SP AF 17-50mm F2.8 XR Di II LD Aspherical IF vs HD Pentax-DA 20-40mm F2.8-4 ED Limited DC WRto review specs, pros and cons, and which is right for you.
Tamron 17-50mm f2.8 XR II LD Top Features
- 17-50mm Focal Range
- F2.8 Max Aperture
- Filter Thread: 67mm
- Max Format: APS-C / DX
- Pentax KAF Mount
- Weight: 430g.
- Diameter: 74mm
- Length: 82mm
- Min Focus Distance:0.27m
- Max Magnification:0.22x
Pentax DA 20-40mm F2.8-4 ED DC WR Top Features
- 20-40mm Focal Range
- F2.8 – F4.0 Max Aperture
- Weather Sealed
- Filter Thread: 55mm
- Max Format:
- Pentax KAF3 Mount
- Weight: 283g.
- Diameter: 71mm
- Length: 69mm
- Min Focus Distance:0.28m
- Max Magnification:0.2x
Our Winner: Tamron SP AF 17-50mm F2.8 XR Di II LD Aspherical IF over HD Pentax-DA 20-40mm F2.8-4 ED Limited DC WR
Focal Length – Wide
17mm
vs
20mm
3mm Wider coverage
Focal Length – Tele
50mm
vs
40mm
10mm more Tele coverage
Optical Zoom
2.90x
vs
2.00x
More flexible focal coverage
Max Aperture – Tele
2.8
vs
4
Wider aperture at tele end
Minimum Focus Distance
0.27m
vs
0.28m
can focus closer to the subject
Max Magnification
0.22x
vs
0.2x
higher magnification better for close-up shots
Diaphgragm Blades
9
vs
7
Potentially more rounded and smooth bokeh
Weight
283g
vs
430g
147g lighter
Diameter
71mm
vs
74mm
3mm smaller in diameter
Length
69mm
vs
82mm
13mm shorter
Filter Thread
55mm
vs
67mm
Smaller filters are cheaper and easier to find
Weather Sealing
Yes
vs
No
safer to use under rain and dust
Image Stabilization
No
vs
No
Reliant on in-body Image Stabilization
Internal Zoom
No
vs
No
Length of the lens changes during zooming
Tamron 17-50mm f2.8 XR II LD vs Pentax DA 20-40mm F2.8-4 ED DC WR All Features
General
Tamron 17-50mm f2.8 XR II LD
Pentax DA 20-40mm F2.8-4 ED DC WR
Brand
Tamron
Pentax
Lens Type
Zoom
Zoom
Price
CHECK PRICE
CHECK PRICE
Lens Type
Standard Zoom
Standard Zoom
Lens Mount
Pentax KAF
Pentax KAF3
Max Format
APS-C / DX
APS-C / DX
Focal Range
17-50mm
20-40mm
Image Stabilization
No
No
Colour
Black
Black, silver
Zoom Method
Rotary (extending)
Rotary (extending)
Power Zoom
–
–
Zoom Lock
Yes
–
Zoom Ratio
2.9X
2.0X
Aperture
Max Aperture
F2.8
F2.8 – F4.0
Min Aperture
F32.0
F22.0 – F32.0
Aperture Ring
No
No
Diaphragm Blades
7
9
Optics
Optical Elements
16
9
Optical Groups
13
8
Special Elements
2 hybrid aspherical elements 1 LD (Low Dispersion) glass element 1 XR
(Extra Refractive) element
1 ED glass element, 1 SLD glass element, HD coating
Focusing
Min Focus Distance
0.27m
0.28m
Max Magnification
0.22X
0.2X
Autofocus
Yes
Yes
AF Motor Type
Micromotor
Micromotor
Full Time Manual
Yes
Focus Method
Internal
Unknown
Distance Scale
Yes
Yes
DoF Scale
Yes
Yes
Distance Scale
Yes
Yes
Focus Distance Limiter
Unknown
Unknown
Physical Specs
Weight
430g
283g
Diameter
74mm
71mm
Length
82mm
69mm
Materials
Unknown
Aluminium barrel
Weather Sealing
Unknown
Yes
Filter Thread
67mm
55mm
Filter Notes
–
–
Hood Supplied
Yes
Yes
Hood Code
flower shaped hood
MH-RA55
Tripod Collar
No
No
Optional Accessories
–
–
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